In general, a library apparatus such as a magnetic tape library apparatus includes a cartridge access unit having a cartridge entry/exit station (which will be referred hereinafter to as a CAS) for loading and unloading a cartridge accommodating a storage medium, e.g. a magnetic tape, a drive unit for performing recording/reproduction of data to and from the storage medium in the cartridge, and an accessor robot (hereinafter "accessor") for moving the cartridge between the access unit and the drive unit.
The CAS of the cartridge access unit includes a rack or shelf for accepting cartridges, and a drive mechanism for rotationally driving the rack so that a cartridge entry/exit portion (entry side) of the rack faces the exterior of the apparatus (the side where the operator operates the apparatus) or the interior of the apparatus (the space side where the accessor moves).
Accordingly, in order to facilitate entry of the cartridge, the rack is rotationally driven by the drive mechanism to expose the cartridge entry/exit portion of the rack to the exterior of the apparatus. After insertion of a cartridge into the rack by the operator, the rack is rotationally driven by the drive mechanism to face the entry/exit portion of the rack to the apparatus interior. Discharge of a cartridge is accomplished by a reverse process. Namely, the rack accepts a cartridge inserted by the accessor in a condition where the entry/exit portion of the rack faces the apparatus interior. Then, the rack is rotationally driven by the drive mechanism to expose the entry/exit portion to the apparatus exterior, allowing the operator to remove the cartridge.
However, in the case of the above-mentioned CAS of the library apparatus, entry/exit of the cartridge requires the cartridge rack to be reoriented by rotationally driving the cartridge rack. Accordingly, the drive mechanism and the rack of such a conventional apparatus must be configured for rotation. As a result, the conventional CAS structure increases the overall complexity and size of the library apparatus.
The present invention has been developed with a view to eliminating this problem. In particular, it is an object of this invention to provide a cartridge entry/exit station and a library apparatus which is capable of achieving the entry/exit of a cartridge while maintaining a simple and compact construction.